GR-78 opinions, anyone?

[Mark Johnson/Ontario/IBM]

Bob, and the rest of the Heath Team....I have a GR-78 and I have done
extensive work on it...I think mine is up to factory spec/operation, but
its a disappointing radio. The audio on mine is a bit distorted IF THE
VOLTAGE DROPS EVER SO SLIGHTLY.
If you have the line cord installed and the voltage is up to spec, its
fine. The gosh durn line cord however can introduce 60hz hum. You can
really hear it if the BFO is turned on. The manual even says you may
encounter this.

I removed the old NICAD and installed 8 Nicad AA cell replacements in a
holder that fit nicely into the radio. They charge OK and run the radio OK,
but if they start to weaken even the slightest bit, the audio distorts. I
tried replacing the audio amp transistors (pre-amp, final stages) and there
was no change. I replaced all the electrolytics, no change......If I want
to use  the radio, I use it on the line cord....Which means, no use of the
BFO...

Alignment was another interesting challenge. I had to do it twice using a
freq. counter and sig generator before I got it on...Its tedious, but just
follow the instructions carefully and take your time....Performance on Band
"F" is very poor....Other bands are OK.....

I'd like to hear your thoughts and progress Bob..Keep us informed....I love
heath stuff, but that radio is a bit of a turkey...Especially when you
factor in its price in 1969 dollars and the performance it gave....I too
think the old GC-1 was better..........Just my opinion....




Mark V. Johnson
VE3DJU/VE3DDI
---------------------- Forwarded by Mark Johnson/Ontario/IBM on 09/16/2001
05:09 PM ---------------------------

"Robert P. Okas" <vintage at BEST.COM>@LISTSERV.TEMPE.GOV> on 09/16/2001
03:26:21 PM

Please respond to "Robert P. Okas" <vintage at BEST.COM>

Sent by:  Heathkit Owners and Collectors List <HEATH at LISTSERV.TEMPE.GOV>


To:   HEATH at LISTSERV.TEMPE.GOV
cc:
Subject:  GR-78 opinions, anyone?


Greetings,

    I'm restoring a GR-78 and have run into some things that lead me to
believe that the radio could be performing better. I'd like to know if my
unit is typical, or if there are some "issues" to address. When compared
to its older brother, the GC-1A, my GR-78 sounds distorted to the point
that I prefer listening to the GC-1A. Nothing severe, but signals sound
rather "fuzzy" and muffled. Does anyone else's radio sound similar?

    All of the voltages that I've measured are within 10% of what the
schematic indicates, so it is working, after a fashion. The speaker and
all other obvious things have been checked and verified. With moderate
signals, I've observed non-linearities in nearly every stage from the IF
strip down.

    I'd like to hear any thoughts, opinions or observations.

TIA,
Bob - W3CD

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